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sunxi: improve throughput in the sunxi_mmc driver

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Throughput tests have shown the sunxi_mmc driver to take over 10s to
read 10MB from a fast eMMC device due to excessive delays in polling
loops.

This commit restructures the main polling loops to use get_timer(...)
to determine whether a (millisecond) timeout has expired.  We choose
not to use the wait_bit function, as we don't need interruptability
with ctrl-c and have at least one case where two bits (one for an
error condition and another one for completion) need to be read and
using wait_bit would have not added to the clarity.

The observed speedup in testing on a A31 is greater than 10x (e.g. a
10MB write decreases from 9.302s to 0.884s).

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>
Tested-by: Mylène Josserand <mylene.josserand@bootlin.com>
Acked-by: Jagan Teki <jagan@openedev.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
This commit is contained in:
Philipp Tomsich 2018-03-21 12:18:58 +01:00 committed by Jagan Teki
parent 4744d81cc0
commit 5ff8e54888
1 changed files with 16 additions and 11 deletions
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27
drivers/mmc/sunxi_mmc.c
View File

@ -188,15 +188,16 @@ static int mmc_update_clk(struct sunxi_mmc_priv *priv)
{
unsigned int cmd;
unsigned timeout_msecs = 2000;
unsigned long start = get_timer(0);
cmd = SUNXI_MMC_CMD_START |
SUNXI_MMC_CMD_UPCLK_ONLY |
SUNXI_MMC_CMD_WAIT_PRE_OVER;
writel(cmd, &priv->reg->cmd);
while (readl(&priv->reg->cmd) & SUNXI_MMC_CMD_START) {
if (!timeout_msecs--)
if (get_timer(start) > timeout_msecs)
return -1;
udelay(1000);
}
/* clock update sets various irq status bits, clear these */
@ -277,18 +278,21 @@ static int mmc_trans_data_by_cpu(struct sunxi_mmc_priv *priv, struct mmc *mmc,
unsigned i;
unsigned *buff = (unsigned int *)(reading ? data->dest : data->src);
unsigned byte_cnt = data->blocksize * data->blocks;
unsigned timeout_usecs = (byte_cnt >> 8) * 1000;
if (timeout_usecs < 2000000)
timeout_usecs = 2000000;
unsigned timeout_msecs = byte_cnt >> 8;
unsigned long start;
if (timeout_msecs < 2000)
timeout_msecs = 2000;
/* Always read / write data through the CPU */
setbits_le32(&priv->reg->gctrl, SUNXI_MMC_GCTRL_ACCESS_BY_AHB);
start = get_timer(0);
for (i = 0; i < (byte_cnt >> 2); i++) {
while (readl(&priv->reg->status) & status_bit) {
if (!timeout_usecs--)
if (get_timer(start) > timeout_msecs)
return -1;
udelay(1);
}
if (reading)
@ -304,16 +308,16 @@ static int mmc_rint_wait(struct sunxi_mmc_priv *priv, struct mmc *mmc,
uint timeout_msecs, uint done_bit, const char *what)
{
unsigned int status;
unsigned long start = get_timer(0);
do {
status = readl(&priv->reg->rint);
if (!timeout_msecs-- ||
if ((get_timer(start) > timeout_msecs) ||
(status & SUNXI_MMC_RINT_INTERRUPT_ERROR_BIT)) {
debug("%s timeout %x\n", what,
status & SUNXI_MMC_RINT_INTERRUPT_ERROR_BIT);
return -ETIMEDOUT;
}
udelay(1000);
} while (!(status & done_bit));
return 0;
@ -405,15 +409,16 @@ static int sunxi_mmc_send_cmd_common(struct sunxi_mmc_priv *priv,
}
if (cmd->resp_type & MMC_RSP_BUSY) {
unsigned long start = get_timer(0);
timeout_msecs = 2000;
do {
status = readl(&priv->reg->status);
if (!timeout_msecs--) {
if (get_timer(start) > timeout_msecs) {
debug("busy timeout\n");
error = -ETIMEDOUT;
goto out;
}
udelay(1000);
} while (status & SUNXI_MMC_STATUS_CARD_DATA_BUSY);
}